Reinforced printing plate



1951 H. H. BORCHERS ETA]. 3,010,394

REINFORCED PRINTING PLATE Filed Feb. 6, 1959 FIGJ FIG.3

w a e 90o INVENIORS HENNING H.BORCHERS THOMAS N. GILLICH y FREDERICK W.VONMEISTER I12 3,010,394 Patented Nov. 28, 1961 3,010,394 REINFORCED PRINTING PLATE Henniug Henry Borchers, Mountainside, Thomas N.

Gillich, North Plainfield, and Frederick W. von Meister,

Peapack, N.J., assignors to Azoplate Corporation, Summit, N.J., a corporation of New Jersey Filed Feb. 6, 1959, Ser. No. 791,727 4 Claims. (Cl. 101-395) This invention relates to printing plates and, more particularly, to flexible printing plates made of aluminum foil or the like.

In the process of offset printing either by duplicator type presses or professional presses, the plates used are generally made from paper or aluminum foil or a combination of both. They may be presensitized or sensitized by the user in the case of photo printing, while in the direct image method an image is produced on the plate either by typing, drawing or printing. By far the greatest portion of cost in the manufacture of such printing plates resides in the expense for the raw material. This is of particular importance with aluminum plates and, in practice, plate thicknesses run from 0.004 inch to 0.0075 inch and higher. ttempts to use aluminum foils thinner than about 0.004 inch to reduce the costs have not been successful since thin foils are frequently damaged during processing even before their installation on the press. Additionally, the frictional forces of the dampener and of the ink roller exerted on the plate'surface during the printing process would tear normal plates of such a thickness from the attaching devices of the press cylinder.

The principal object of the present, invention is, therefore, to reduce the cost of printing plates by arrangements which permit the use of aluminum or paper printing plates having substantially smaller thickness than that of pn'nt-' ing plates used heretofore. The initial cost, the shipping weight and the space required for storage would then be greatly reduced.

In accordance with the invention these objects are achieved by the use of a comparatively thick reinforcing plate or sheet in combination with printing plates which may be thinner than any of the currently employed plates. Such a reinforcing plate can be removably attached to that plate which actually is intended to be used. As a result, one reinforcing sheet can be utilized repeatedly in conjunction with a great number of printing plates or foils one after the other. Whenused with printing plates having marginal perforations which cooperate with attachment hooks on the press cylinder, the reinforcing sheet is provided with similar perforations so that the printing plate and the reinforcing sheet are secured to each other and to the press cylinder by means of the mentioned hooks. In practice, the plates have, suitably, two marginal strips bent backwardly alongside of each of two opposite edges to form a pair of folds or channels facing each other. At first, the reinforcing sheet having the size of the fiat area of the printing plate between the marginal strips, is inserted into the folds. By means of the hooks on the cylinder of the press and the perforations, the reinforced printing plate is subsequently attached to the press cylinder in the same fashion that thicker plates were handled heretofore. As a result, the backwardly bent marginal strips take the stresses which, otherwise, would be carried by the edges of the perforations in the plate.

On the other hand, when intended for use with printing presses provided with clamps, the perforations are omitted and the increased thickness of material maintained in the clamps afiords an improved resistance against tear.

The invention will be further iliustrated by reference to the accompanying drawing in which:

FIGURE 1 is an isometric view of a reinforced printing plate;

FIGURE 2 is a sectional view taken on line 2-2 of FIGURE 1 and looking in the direction of the arrows; and

FIGURE 3 is a front view of a reinforcing sheet.

Referring to the drawing, the substantially flat area 10 constitutes the useful surface of a printing plate and is coated with a layer 12 of a light sensitive material, which is exposed to light under a master and subsequently developed. However, it will be noted that the area 10 may be processed by any other known method to form a reproducible image. Such a method, distinct from that using presensitized plates, may include a special preparation of the plate followed by subsequently applying the image thereon by typing or drawing. The useful area 10 continues into at least one, preferably two marginal strips 14 and 16 which are folded backwardly at each of two opposite edges 18 and 20 of the flexible plate. By this operation two folds or channels are formed which face each other to re-' ceive a reinforcing sheet 22 having a thickness of about 0.004 inch. As shown in FIGURE 1, the fiat area 10 and the two backfolds 14 and 16 envelope the reinforcing sheet 22 between themselves and the adjacent portions of the nonprocessed surface of the area 10. Suitably, the sheet 20 has a shape and size identical to that of the area 10 or slightly smaller.

In order to permit securing of the printing plate assembly to the cylinder of a printing press, or of a duplicator such as a 1250 Multilith as made by the Addressograph-\dultigraph Corporation of Cleveland, Ohio, for example, a row of perforations 24 is provided alongside of each of the edges 18 and 20. Corresponding perforations through the backfolds 14 and 16 are designated by numeral 26 in FIGURE 2. The reinforcing sheet 2-2 (FIGURE 3) has perforations 28 arranged identically with those in the printing plate and the backfolds. After inserting the reinforcing sheet into the folds or channels, the perforations 24 along the edges of the area 10, the perforations 28 in the reinforcing sheet 22 and the perforations 26 in the backfolds 14 and 16 are aligned for conveniently attaching the assembly to the cylinder of a printing press or a duplicator.

Due to the fact that mechanical stresses caused by friction of the dampener and ink rollers are distributed over the entire length of the marginal area of the assembly, very thin printing plates can besuccessfully used. Tests revealed that suitable reinforcing sheets have a thickness inlhe range of 0.002 inch to 0.006 inch and a tlu'ckness of about 0.004 inch has been found to give good results. In conjunction with these reinforcements, printing foils of 0.002 inch thickness or less can be used, so that their costs, the shipping weight and required storage space are greatly reduced.

According to a modified embodiment of the invention, the reinforcing sheet may be provided with the backfolds and the printing plate may be a simple flat sheet. Referring to the drawing, this means that the roles of the plate and of the reinforcement are reversed. More particularly, in FIGURE 2-, numeral 10 would then desighate the thicker reinforcement having backwardly folded marginal strips 14 and 16. In this case the printingplate 22 would be a plain sheet of which the bottom side in FIGURE 2 has been processed to form a reproducible image, as described above.

In addition to the modification mentioned above, it is possible to eliminate one of the backfolds 14 or 16. When such a change is effected, however, care must be taken to place the backfold at the leading edge of the not exceeding about 0.004 inch and one removable integral reinforcing sheet having a thickness in the range of 0.002 inch to 0.006 inch, the plate having a substantially flat area which continues into at least one mar? ginal strip folded backwardly over one edge of the fiat area to form a fold, the reinforcing sheet having substantially the size of the flat area to be fitted between the fiat area and the fold, the fold and the reinforcing sheet being provided with marginal rows of perforations for securing the plate-reinforcing sheet assembly to a printing press, whereby the reinforcing sheet takes the tensioning stress during operation of the press.

2. In combination, a printing plate made from a material selected from aluminum foil and paper having a thickness not exceeding about 0.004 inch and on removable integral reinforcing sheet having a thickness in the range of 0.002 inch to 0.006 inch, the plate having a substantially fiat area which continues into at least one marginal strip folded backwardly over one edge of the flat area to form a fold, the reinforcing sheet having substantially the size of the flat area for enveloping it between the flat area and the fold, the fold and the reinforcing sheet being provided with marginal rows of perforations for securing the plate-reinforcing sheet assembly to a printing press, whereby the reinforcing sheet takes the tensioning stress during operation of the press. 3. In combination, a printing plate and a removable integral reinforcing sheet, the printing plate having a substantially fiat area which continues into at least one marginal strip folded backwardly over one ed e of the that area to form a fold, the reinforcing sheet having substantially the size of the flat area to be fitted between the flat area and the fold, the fold and the reinforcing sheet being provided with marginal rows of perforations for securing the plate-reinforcing sheet assembly to a printing press, whereby the reinforcing sheet takes the tensioning stress during operation of the press. 4. In combination, a printing plate and a reinforcing sheet, the reinforcing sheet forming one integral unit physically separate from the printing plate, the plate having a substantially flat area which continues into at least one marginal strip folded backwardly over one edge of the fiat area to form a fold, the reinforcing sheet having substantially the size of the'flat area to be fitted between the fiat area andthe fold, the fold and the reinforcing sheet being provided with marginal rows of perforations for removably securing the same reinforcing sheet selectively toa series of printing plates each in succession, in an aligned arrangement, and both to a printing press, whereby the reinforcing sheet takes the tensioning stress during operation of the press.

References Cited in the file of this patent UNITED STATES PATENTS 2,937,593 Ritzerfeld et a1. May 24, 1960 

